Like many of the components in Maemo, File Manager is not open source so only Nokia could implement it in File Manager directly. And as this is in Brainstorm, good luck with that...

That said, what the open source community can do is to implement it in libhildonfm2 itself. This is not, really, a good idea as it would involve the replacement of a system library and the best place I found where I could implement my "adding sharing of files to the file manager" hack (this was before I wrote Petrovich) was in the Details dialog. Not the most convenient of places.